In the past, there has been great difficult in providing a loudspeaker covering the mid and high frequency audio range at high quality. Directivity varies greatly in this range, and extension to the highest frequencies is very difficult for mid driver alone. Typically, two drivers are used with the expense and complication of a crossover network to divide the frequency range between them. The crossover frequency is generally around 3 kHz which is the most sensitive in human hearing which adds to the difficulty.
The concept of the present invention is to devise a mid and high frequency driver which replaces the two conventional drivers previously used, which does not crossover in the critical region and which has consistent, desirably wide directivity throughout its working range.
Distributed mode loudspeakers can be designed to operate over some 8-Octaves of the audio frequency band, although this may not always be the best solution, for instance in hi-fi applications. It is envisaged that it might sometimes be appropriate for a distributed mode loudspeaker to be used in association with a subwoofer for low frequencies, crossing over, say, at around 100 to 200 Hz.
There is therefore a need for a loudspeaker or at least a loudspeaker drive unit that is not meant to necessarily work over 8-Octaves but perhaps over 6 to 7 Octaves of the audio band, which would allow a wide choice of material and various construction possibilities that would help optimise the loudspeaker fully over its operating range. An example of this is a hi-fi midrange/tweeter drive unit working under the distributed mode loudspeaker principle. This can bring significant benefits to a conventional boxed loudspeaker system by allowing the cross-over point to be designed away form the critical 3 kHz area down to 1 khz range, typically 300-500 Hz as well as benefiting from the superior radiation properties associated with a distributed mode loudspeaker.
There is also an expanding market in multimedia and computer peripherals for high performance compact speakers and ever increasing demand for better sound and more compact construction for conventional televisions, monitors and flat panel televisions.
Thus there is a need for a structure that can be very compact and which can allow numerous features to be added for performance enhancement, application versatility and cost saving.
The present invention provides a cost-effective vehicle for all such applications and allows a manufacturer to optimize on tooling outlay and its production processes.
The basic concept revolves around a simple construction of the loudspeaker "engine" or drive unit which would allow easy production assembly and provide consistency.